The presence of chloride ions in reinforced concrete is known to be deleterious and it has been previously proposed to remove chloride ions by a process which has become known as desalination. This process has been described in European Patents Nos. 200,428 and 398,117 and involves passing an electric current through the concrete by applying a voltage for example 3 to 15 volts between an external temporary anode and the steel reinforcement in the concrete. The external temporary anode is usually covered in a layer of electrolyte which often includes in addition to the electrolyte an adherent coating material. The effect of the electric current is to cause chloride ions within the concrete to migrate through the concrete towards the surface and into the electrolyte layer. European Patent No. 398,117 describes the use of a fibrous cellulose pulp in the coating and the mixing of the pulp fibres with a liquid to form a self adherent material which is applied to the exterior surface of the concrete by spraying whereby an anode which has been previously applied to the concrete surface is embedded in a fibrous cellulose coating. Loss of alkalinity in reinforced concrete is also known to be deleterious. The loss of alkalinity is caused by carbon dioxide and other atmospheric gases such as sulphur dioxide. A process for increasing the alkalinity of concrete whose pH has been reduced by atmospheric gases has been previously described in European Patent No. 264,421 and U.S. Pat. No. 4,865,702. In this process an electric current is passed between an externally applied electrode which is in contact with an alkaline solution and the internal reinforcement of the concrete as cathode. The result of the process is to increase the concentration of hydroxyl ions in the region of the reinforcement and thereby increase the alkalinity of the concrete. The benefit of doing this is that corrosion of the reinforcement is reduced or prevented. The process has become known as realkalization.